The Earth’s Climate System

Is climate change new?Climate change is a natural part of Earth’s history. For example, thousands of years ago, thick ice sheets covered most of Canada and a large portion of the United States.

Key Terms• Weather refers to the

condition of the atmosphere at a specific place and time. It describes factors such as wind, temperature and humidity.

• Climate refers to the condition of the atmosphere over a large area, averaged over many years.

Temperature and ClimateTemperature and Climate

• The Earth is surrounded by The Earth is surrounded by an envelope of gases an envelope of gases called the called the atmosphereatmosphere..

• Without this envelop, the Without this envelop, the days would be too hot and days would be too hot and the nights would be too the nights would be too cold!cold!

• So how is heat energy So how is heat energy transferred?transferred?

How is Heat Transferred?• Heat is always transferred from the hotter object to

the colder object. • There are three types of heat transfer:

Conduction

• The transfer of heat between substances that are in direct contact with one another

• The better the conductor the more rapidly the heat will transfer.

Convection• The up and down movement of gases and liquids caused by

heat transfer. • As a gas/liquid is heated it expands and rises because it is

less dense. As it rises and expands, it cools and falls. This creates convection currents.

Radiation• Electromagnetic waves moving through space.

These waves come in contact with an object and transfer the heat to the object.

Earth’s Climate System

• A complex framework of interactions between various factors that influence the Earth’s climate.

Earth’s Climate SystemsWhat does it involve?• Atmosphere •Lithosphere

These components interact with one another and with aspects of Earth’s biosphere to determine not only day-to-day weather, but also long term averages, climate.

• The Hydrosphere

1. The Sun 2. The Earth

3. The Atmosphere 4. The Hydrosphere

   

5. Human Activity

Factors Affecting Climate Change

1. The Sun 2. The Earth

3. The Atmosphere 4. The Hydrosphere

   

5. Human Activity

Factors Affecting Climate Change

Solar Energy• The most important factor that affects climate is the sun• Earth’s climate systems are driven by radiation energy

received from the sun.• The intensity of the energy that reaches Earth’s surface

affects the temperature of air, water and land• Heat produces winds, rain and other features of climate.

Changes in Solar Activity

• The Sun produces a variable amount of energy.

• When the number of sunspots is high, the Sun emits higher amounts of solar radiation.

• Some scientists believe that changes in solar output are the main cause of climate change in the past.

1. The Sun 2. The Earth

3. The Atmosphere 4. The Hydrosphere

5. Human Activity

Factors Affecting Climate Change

Factors on Earth that Affect Climate

1.Rotation2.Revolution3.Tilt4.Latitude

Solar Energy and the Earth• The amount of solar energy that reaches Earth

depends on solar activity, the shape of the Earth and the tilt of the Earth.

Rotation vs. Revolution a Review• Earth rotates once every 24 hours (1

day) around its axis, an imaginary line that goes from the North Pole to the South Pole through the center of the Earth.

• The Earth also revolves (orbits) around the Sun every 365 and a half days (1 year).

• Another important detail is that the Earth’s axis of rotation is tilted at an angle of about 23.5˚

The seasons are created by Earth’s revolution and its tilted axis.

Earth’s Seasons

Latitude

• Energy coming from the sun is not distributed uniformly across the surface of the Earth.

• Due to the shape of the Earth, the energy is most intense at the equator and weakest at the poles.

Temperatures Around the World

• This non-uniform energy distribution leads to temperature differences.

Land Surfaces • Earth’s outer layer is made of massive pieces of solid rock,

called tectonic plates.• Earth has about 12 major plates that move at a rate of a few

centimeters per year. • The plates carry the continents with them as they move.

• This means that the shape of the oceans and continents is always changing.

The Movement of the Continental Plates

• Patterns of air and water circulation are affected which in turn affects the thermal energy around the world.

• The formation of mountain chains also affects the patterns of wind and precipitation around the globe.

Volcanoes• Most volcanoes are located at the boundaries of

tectonic plates.

• Plate movement affects climate by producing volcanic activity.

• In these areas, molten rock and gases from below the Earth’s crust rise up through cracks in the rock and spew into the air as volcanic eruptions.

Volcanic Eruptions• During a volcanic eruption, particles called

aerosols (such as ash) are released into the atmosphere.

• Aerosols reflect solar radiation, having a cooling effect on the global climate, and scatter light

• Some volcanic eruptions can raise global temperatures by releasing greenhouse gases.

1. The Sun 2. The Earth

3. The Atmosphere 4. The Hydrosphere

5. Human Activity

Factors Affecting Climate Change

Atmospheric Factors that Affect Climate

1.Greenhouse Effect2.Wind

The Atmosphere… Earth’s Warm, Snuggly Blanket

• The Earth’s atmosphere is like a big blanket that surrounds the globe keeping humans warm. If it was suddenly stripped off, the Earth’s average temperature would plummet and everything would freeze.

• Like a blanket that could be made from a mix of cotton and wool, the Earth’s atmosphere is made from a mixture of gases.

The Earth’s AtmosphereThe atmosphere starts at Earth’s surface and goes up to about

560 km into space.

It is mostly made of nitrogen (N2) and oxygen (O2) gases as well as water vapour, very low concentrations of other gases and particles of solids.

The Greenhouse EffectA natural process that keeps Earth’s temperatures within a certain range.

Without it Earth’s average temperature would be colder (approximately 34˚C lower) and most of the solar energy reaching Earth would radiate out back into space.

The atmosphere contains greenhouse gases and solar radiation passes through them. Solar radiation warms the surface of the Earth and heat rises from the surface

Some heat is able to pass back through the gases and some cannot. The heat that is trapped adds to overall global temperatures.

Wind• Wind is caused by uneven heating of Earth’s surface.• The air moves as wind transfers thermal energy around the

world from warm areas to cooler areas. • It is the movement of air from an area of high pressure to an

area of lower pressure.

Prevailing Winds• Winds blow in fairly constant directions around the

world. These are known as prevailing winds.

Wind

• Winds disperse energy throughout the atmosphere.

• The movement of air affects: – precipitation patterns– ocean currents

Precipitation• As air masses of different densities move across

the Earth’s surface, they interact.• When air masses meet (called a front), one air

mass usually rises over the other.• The rising air cools and any water vapour in the

air condenses to form precipitation.

Ocean Currents• The difference in atmospheric temperature cause the

ocean to react and create convection currents. These currents transport heat from the warm tropics to the cold Polar Regions and back again.

1. The Sun 2. The Earth

3. The Atmosphere 4. The Hydrosphere

5. Human Activity

Factors Affecting Climate Change

The Hydrosphere• Two thirds of the Earth is covered by oceans.

• The hydrosphere includes all of the water on the planet in its different forms.

• On Earth water is found in many forms:– vapour and clouds of water droplets in the

atmosphere– liquid in the oceans, seas, and smaller bodies of

water– ice and snow in temperate and colder regions

Gas Liquid Solid

The Hydrosphere

Specific Heat Capacity• Oceans and lakes act as heat reservoirs. They buffer

temperatures in the atmosphere.• Large bodies of water influence climate because

water has a large specific heat capacity compared with other substances.

Specific Heat Capacity• Specific heat capacity is the amount of heat

required to raise the temperature of one gram of a substance by one degree Celsius.

• Water has a large specific heat capacity. This means it takes more heat to raise the temperature of 1 g of water by 1oC than it does to do the same to many other substances.

Specific Heat Capacity… So what?• The higher the heat capacity, the longer it takes to warm the

substance up and the slower the substance loses its heat. • Water’s high specific heat capacity means that a land mass

near a large body of water will have its temperature “moderated” by the water – it will warm up more slowly in summer and cool down slowly in winter than will a land mass further from water.

The water will warm and cool more slowly than the beach

20 degrees

25 degrees

Specific Heat CapacitySome Common Specific Heat Capacity Values

Substance Specific Heat Capacity in “The number of joules of heat energy needed to raise the temperature of 1 g of the substance by 1oC.”

Pure Water 4.18

Sea Water 3.89

Dry Air 1.00

Wet mud 2.51

Sandy soil 0.92

Snow and Ice• Ice and snow reflect heat• The light colour of ice and snow allow them to

reflect solar radiation. • Because as we know, light-coloured surfaces

reflect energy, and dark surfaces absorb energy.

Ice and Snow Reflect Heat• The light colour of ice and snow allow them to reflect solar

radiation.

The amount of energy that is reflected by a surface is known as albedo.

• Light-coloured surfaces reflect energy, and dark surfaces absorb energy.

Example:

• Because of their large differences in albedo, the distribution of water, ice and land on Earth’s surface greatly affects the average global temperature.

1. The Sun 2. The Earth

3. The Atmosphere 4. The Hydrosphere

5. Human Activity

Factors Affecting Climate Change

Burning of Fossil Fuels

Climate Systems Recap

• What are 3 ways that heat is transferred? Povide a diagram.

• Compare and contrast weather and climate.

• What are the 5 main influencing factors on Earth’s climate system?